| Strawberry (Fragaia ananassa Duchesne) is very popular for their succulent tissue and richness in nutrient.However, there is short mature period and concentrative ripening period for strawberry.Meanwhile, due to the soft tissue and high water content of strawberry fruit and easily infected by postharvest disease. The major postharvest fungal disease is grey mold decay caused by Botrytis cinerea in strawberry. So far, many chemical have been used for postharvest which have potentional danger for people’s healthy. Therefore, appropriate methods for improving posyharvest quality and preventing strawberry fruit from pathogens in transportation and storage are urgent for strawberry fruit.The study was designed to investigate the effect of hot air and MeJA treatment on postharvest quality and botrytis in strawberry fruit from two angles,inhibiting the growth of pathogen and the possible mechanism involved.Than comparing the differences between HAT and MeJA treatment.The results were as follows:1. The effect of hot-air treatment on the quality of strawberry was evaluated by two second order quadratic equations for HAT with help of response surface method (RSM) with different temperature(42-48℃), time(2-4h),while chosing disease index and firmness as response factors. The adequacy of the model equation for predicting the optimum response values was verified by the analysis of 3D graphs and contour maps.The optimum hot air temperature is 43℃ and exposure time is 3 h.2. Compare the effect of hot air (45℃ for 3.5h) and 10μmol/L methyl jasmonate treatment on quality and antioxidant activities in strawberry fruit during storage at 20 ℃.The results showed that the two treatments can both significantly control decay, delay softening and the reduction of total flavonoids and vitamin C, and boost the content of total phenolics. Meanwhile, improving the expression of quality related genes including flavonol synthase, chalcone synthase and phenylalanine ammonialyase, decreasing the expression of beta xylosidase. However, hot air traerment restrain the accumulation of anthocyanin and expression of anthocyanidin synthase gene, while MeJA treatment has the opposite effect. The study demonstrated that these two treatments can maintain fruit quality and antioxidant activity by regulating the expression of quality related genes.3. Compare the effect and possible mechanism of hot air (45℃ for 3.5h) and 10 μmol/L methyl jasmonate treatment on botrytis resistant of strawberry fruit. The results showed that the two treatments can both significantly control the extension of scab, boost the accumulation of phenolics and phytoalexin, and improve the activity of defense-related enzymes ncluding β-1,3-glucanase, chitinase and PAL in strawberry fruit.Reverse transcription experiments showed that single hot air treatment and inoculation after hot air treatment can both qaulity stimulate the higher expression of defense-related genes PAL6, CCR-allele and CAT. Whereas, only by inoculating after 10 μmol/L MeJA treatment can significantly induced the higher expression of defese-ralated genes. The in vitro studies have shown that MeJA can not directly inhibiting spore germination and germ tube elongation of B. cinerea, but hot air treatment can. In conclusion, these results suggested that hot air treatment can significantly enhance disease resistance of strawberry fruit by inducing the activity and gene expression of defense-related enzymes and directly restrain the growth of pathogen. While, MeJA reduce fruit decay effectively possibly by priming action for "preserve the disease resistance", rather than a direct inhibitory effect on pathogen growth. |
